Automatic steering device



Dec. 29, 1931. E. A. SPERRY AUTOMATIC STEERING DEVICE 2 Sheets-Sheet Filed Nov. 1926 To P4475 i 'll. u 7///////////////////////////////////////////////I/// rl//////////////////////////// 0 H H "a Z 0 T Dec. 29, 1931.

E. A. SPERRY 1,838,965

AUTOMATIC STEERING DEVICE Filed Nov. 1926 2 Sheets-Sheet 2 INVENTOR automatic steering device ineffective,

Patented Dec. 29, 1931 PATENT orrics ELMER A. SPERRY, OF BROOKLYN, NEW YORK,

TO SPERRY GYBOSCOPE COMPANY, INC., OF NEW YORK ASSIGNOR, BY MESNE ASSIGNMENTS, OF BROOKLYN, NEW YORK, A. CORPORATION A'IIVJIOIIYIIA'IIC STEERING DEVICE Application filed November 27, 1926. Serial No. 151,175.

This invention relates to the automatic steering or control of dirigible craft. Theinvention contemplates the use of the earth inductor com ass as a baseline in combination with means or overcoming the major difliculty inherent in the use of such baseline, namely, that the forces generated by the earth inductor compass are necessarily small and very little or practically no load can be placed thereon. For this purpose I employ in combination with the earth inductor compass a frictionless control unit for rendering effective a suitable servo motor for actuating the rudders or other control elements of the craft.

It is a further object of my invention to provide an automatic steering device of the kind described above, wherein the speed of actuation of the control rudder or other control elements may be varied.

A further object of this invention is the provision of a wind-driven servo motor of variable capacity for actuating the direction control elements.

A further object of this invention is the provision of means for readily rendering the when, for example, hand.

Further objects and advantages of this invention will become apparent in the following detailed description thereof.

In the accompanying drawings Fig. 1 is a vertical section through an earth inductor compass forming part of my automatic steerin mechanism, in combination with means whereby a new course may be set at will.

Fig. 2 is a wiring diagram of the frictionless control unit actuated by the earth inductor compass.

Fig. 3 is a detail showing means for varying the capacity of the control condenser shown in Fig. 2 so that the sensitivity of the system may be correspondingly varied.

Fig. 4 is a vertical section through a winddriven servo motor, parts of said motor being broken away.

Fig. 5 is an elevation of the direction control and clutching mechanism.

the device is to be steered by Fig. 6'is a vertical section taken substantially on line VI-VI of Fig. 4.

ig. 7 is a view, partly sectioned horizontally, of the mechanism shown in Fig. 6. 1 Referring to Fig. 1 of the drawings, I have therein disclosed a form of earth inductor compass adapted for the needs of the automatic steering mechanism described herein. Said compass may be enclosed within an elongated cylinder casing 10, said casing being suspended for universal movement in gimbal rings 11 and 12 so that the suspension of said casing in said rings is slightly pendulous, suitable weights 1314 being supplied for counter-balancing purposes, and suitable supporting bearings 28 being provided for supporting the compass as a whole. Within the cylinder 10 there is mounted a D. 0. motor, comprising the armature 14' and field coils 15, said motor being supplied with energy from some means, such as a storage battery feeding current into said motor through slip rings 16 mounted on the outer gimbal. Thearmature is mounted for rotation about a vertical axis and is suitably supported in bearings, the shaft 17 of said armature driving the armature 18 of a D. C. generator whose field is supplied by the magnetic field of the earth. Armature 18 carries a com mutator- 20 with which cooperate brushes 21 fixed to the casing 10 so that by rotating the casing the brushes may be turned about said commutator 20. The principle of the earth inductor compass is well known and it will readily be appreciated that when the brushes 21-21 are in line with the earths magnetic field, no voltage will be established or current generated. When, however, the brushes 2121 turn out of line with the said earths magnetic field, voltage is generated and this voltage is utilized to actuate the rudder and bring the craft'back to its original position, that is, the position wherein brushes 2121 are in line with the earths magnetic field.

From the above description, it will be appreciated that the craft may be set originally on any predetermined course by merely rotating the casing 10 to rotate the brushes 21 with respect to the earths magnetic field to the desired extent and maneuvering the craft until it is found that no voltage is generated. This may be effected by suitable means, such as, for example, that s own in Fig. 1, Where outer gimbal ring 12 may be provided with an annular gear with which may mesh gearing 22 to 24, which may be operated from a distance through a cord and pulley arrangement 25 to 27 by the operator. Said actuation would merely comprise rotating a spring-roller 30 in the proper direction to cause rotation of casing 10 against the action of a restoring spring 29, the gearing 22-24 being preferably a multiplying gearing so that a small actuation of roller 30 will cause a large actuation of casing 10. The roller 30 maybe normally held in position by a snubbing post or spring-brake device 31 so that when the spring is contracted, the brake is released and the roller may be freely operated. The operation of the earth inductor compass in the automatic steerin' device will be apparent. If a course has een set by suitably positioning the brushes 21, the craft is manipulated until no voltage is generated by the earth inductor compass, whereupon the operator may know that the craft is on its course. Thereafter-any deviations from the course will cause brushes 21 to move out of parallelism with the earths magnetic lines to generate an E. M. F. in one direction or the other which will cause movement of pointer 40 to the right or left depending on the direction of deviation as is well understood in earth inductor compasses and consequently cause relative movement between g condenser member 41 and superimposed members 42 and 43 which will actuate the servo-motor mechanism (to be hereinafter described) through relay R to position the rudder so as to bring the craft back to its course, that is to say, so that brushes 21 are moved back to the original setting, that is, in line with the earths magnetic field. A follow-up (not shown) may be provided between the rudder and condenser members 42 and 43, as is usual in such devices.

The mechanism whereby movement. of brushes 21 out of line with the earths magnetic field will cause actuation of the rudder is disclosed in the remaining figures of the drawings. Referring to Figs. 2 and 3, it will be seen that I have provided a combined galvanometer and condenser so that whenever brushes 21 move out of line with the earths magnetic field and a voltage is generated, the needle 40 of said instrument 39 will be actuated and the lower end of said needle may carry a plate 41 (see Fig. 3) which will move with respect to and in between plates 42-43 of the condenser to vary the capacity of said condenser. Said condenser may form part of an oscillatory circuit comprising the usual audion. tube 45, having a plate P, grid G and filament F, having current supplied to said elements .by the usual A, B and C batteries. Such a circuit may be normally oscillatory so that increase in the capacity of condenser 41 to 43 may cause the circuit to become non-oscillatory or in the opposite sense, the circuit may be normally non-oscillatory so that increase in the capacity of said condenser causes to cease oscillating with resultant increase in the current passed. Such increase of current in the clrcuit excites the magnet R strongly enough to actuate a double contact circuit closer in one direction against the action of a spring S which normally main tains the contact closed in the other direction thus biasing the rudder to turn the plane in contrary direction to the direction in which the plane is turned when contact is closed by the action of magnet R. It is only when the current in the coil becomes great enough to overcome the tension of the spring that the armature will be attracted by the coil to close the front contacts and cause the motor M to operate in the opposite direction and thus actuate the rudder and follow-up element including the condenser in the opposite direction. When said. condenser has overrun its neutral position then the relay will become sufficiently weak to permit the contact to close in the opposite direction by the spring S so that the servo-motor system continually oscillates or reverses about its position of equilibrium. Motor M, which may have a very light substantially inertialess armature is shown as cont-rolling a Bethlehem ear or torque amplifier 50. The power shaft 53 drives the clutch gears 50 and 50" in opposite directions by means of intermeshing pinions 51 and 51'. Dependin upon the direction of rotation of motor LE one or the other of clutch members 50', 50"

will be rendered effective to transmit the drive from power shaft 53 to turn gear 54 an amount proportional to the rotation of motor M and in a corresponding direction. Said gear 54 may drive the rudder control drum 55 through gearing 57 Preferably one of the gears 54, 57 (in the present instance gear 54) is loose on 1ts shaft and adapted to be connected thereto through some means such as anelectric clutch 58 which can be actuated at will by the operator by switch 58 to render the automatic steering control effective or ineffective.

The ower for driving shaft 53 may be obtained rom a wind-driven servo motor shown in Fig. 4 comprising a rotatable cap 60 carrying blades 61 and operating through gearing 62-63 to drive a shaft 53' geared to the said shaft 53.. The angular position of the blades 61 with respect to the plane of travel of the craft will determine the speed of operation of shaft 53 and, therefore, I provide means whereby the said angularity may be varied to control the speed of said motor. For this purpose the blades 61 may each comprise a the circuit stub-shaft 65, which carries at its inner end one end of a bell crank 66, the other end of which has a pin and slot connection 67-68 with a block 69 slidable relative to a fixed tube 70. Said block is normally held against said tube by means such as a spring 71 fixed to said block and to a fixed head 72, and in this position the blades 61 are adapted to have their maximum effective angularity, i. e., to give maximum speed. It will be seen, however, that if block 69 is moved away from the end of tube 70, bell-cranks 66 will be rocked to decrease the effective angularity of blades 61 progressively and hence decrease the speed of the motor from maximum to zero, in which latter position the wind-driven servo-motor will be entirely ineffective. For so controlling the speed of the motor I provide means such as cable 75 operating one fixed roller 7 6 to actuate a driver 77 against the action of a restoring spring 7 8 to force a tube or plunger 80 operating within tube against block 69 to move said block away from tube 70 to any desired extent to control the speed of the motor or to render said motor totally ineffective as hereinbefore set forth.

In accordance with the provisions of the patent statutes, I have herein described the principle and operation of my invention, to-

gether with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other means. Also, while it is designed to use the various features and elements in the combination and relations described, some of these may be altered and others omitted without interfering with the more general results outlined, and the invention extends to such use.

Having described my invention, what I claim and desire to secure by Letters Patent 1s:

1. In an automatic steering mechanism for dirigible craft having a rudder and a servo motor for actuating said rudder, in combination, an earth inductor compass comprising a generator and an indicator, a substantially frictionless non-torque applying, non-contacting controller including an oscillatory circuitactuated by said indicator for controlling said motor, and manual means for changing the course including means forshifting the position of said generator on the craft.

In an automatic steering mechanism for dirigible craft having a rudder and a servo motor for actuating said rudder, in combination, a enerator rotated in the earths magnetic eld, course-settin means whereby turning of said craft with respect to the earths magnetic field causes said generator to generate an E. M. F., a relay includmg an oscillatory circuit for controlling said motor, and means whereby said induced I steering the vehicle,

E. M. F.- varies the reactance in said circuit.

3. In an automatic steering mechanism for dirigible craft having a rudder and a servo motor for actuating said rudder, in combination, a generator rotated in the earths magnetic field, course-setting means whereby turning of said craft with respect to the earths magnetic field causes said generator to generate an E. M. F., a galvanometer controlled thereby, a relay including an oscillatory circuit for controlling said motor, said circuit including a variable condenser on said galvanometer, and means whereby variations in the condenser causes said relay to actuate the servo-motor in one direction or the other for maintaining the craft on its course.

4. In an automatic steering device for dirigible vehicles, a generator adapted to be revolved in the horizontal component of the earths magnetic field, means for adjusting said generator so that the output is a minimum when the vehicle is on its predetermined course and for changing said adjustment to change the course, a direction indicator actuated from said output, a servo-motor for an oscillatory electric circuit for controlling said servo-motor, and a variable means in said circuit and moved by said indicator for varying the reactance of said circuit to control said servo-motor.

5. In an automatic steering mechanism for dirigible craft having a rudder and a servo motor for actuating said rudder, in combination, an earth inductor compass, means for adjusting said compass to generate a predetermined potential when the craft is on the course whereby deviation from the course alters said potential, a galvanometer in circuit with said compass, a frictionless non-contacting, non-torque applying or mere influence linkage for actuating said servo-motor from said galvanometer including an oscillatory electric circuit, a thermionic valve in said circuit, and means brought into action by move ment of said galvanometer for varying the reactance of said circuit to drive said servomotor in the proper direction said craft on its course.

In testimony whereof I have aflixed my signature.-

ELMER A. SPERRY.

to maintain 

